Air-cooler for internal-combustion turbines



D. EYRE AIR-COOLERS FOR INTERNAL-COKBUSTION TURBIRES Feb. 3, 1948.

Filed Oct. 8, 1943 4 Sheets-Sheet 1 is plus Euro? M4. if a 2 M4 ATmRYE-I Feb. 3, 1948. D. EYRE 2,435,557

AIR-COOLERS FOR INTERNAL-COMBUSTION TURBINES Filed Oct. 8, 194:5 4 sheets-sheet 2 l/wavralr 4 Ma m Feb 3, 1948. D, EYRE 2,435,557

AIR COOLERS FOR INTERNAL-COMBUSTION TURBINES Filed Oct. 8, 1943 4 Sheets-Sheet 3 //v VENTO A Feb. 3, 1948. D. EYRE AIR-COOLERS FOR INTERNALCOMBUSTION TURBINES 4 Sheets-Sheet 4 Filed Oct. 8, 1943 YIVYENTOK 41' T0 RIVA-Y Patented Feb. '3, 1943 AIR-COOLER FOR INT ERNAL-COMBUSTION TURBINES Donald Eyre, Alvaston,.Derby, England, assignor to Rolls-Royce Limited, Derby, England, a Brit- 'ish company Application October 8, 1943, Serial No. 505,550 In Great Britain November 5, 1942 9 Claims. (CI. 60-41) This invention relates to internal-combustion turbines of the kind in which a compressor delivers compressed air to a combustion chamber into which fuel is delivered by a rotating burner, the products of combustion passing from the combustion chamber through the turbine, and in which the fuel is delivered to the burner through an air-cooler through which also flows a portion of the air delivered by the compressor so that this air is cooled by the fuel. The cooled compressed air may be used for pressure balancing or cooling purposes in the compressor and turbine or for any other purpose for which it is needed. Since the burner is rotating it must be supplied with fuel through a collecting ring rotating with the burner and astationary feed to that ring. The object of the present invention is to provide an improved air-cooler foran internal-combustion turbine of the above kind.

According to the present invention there is provided an internal-combustion turbine of the above kind wherein the air-cooler is constituted by a plurality of passages rotating with the. burner, connecting, and conveying fuel from, the collecting ring to the burner, and spaced apart to provide between them air passages communicating .at one end with the delivery from the' compressor and at the other end with a spacein which cooled compresed air is required. With this construction the air-cooler rotates with the burner and this has the advantage that it can be made smaller and that the connections by which the fuel is fed to the burner can be made simpler than is possible whenthe air-cooler is stationary and the fuel must be conveyed from it to the rotating burner.

Preferably, the fuel passages are spirally arranged around the axis of rotation of the burner so that the ends of the airpassages between them that communicate with the delivery of the compressor, face in the direction of rotation of the burner, whereby the rotating of the aircooler with the burner causes a flow of air through the air passages in the correct direction. Conveniently, the fuel passages are formed by flattened tubes each longitudinally corrugated on one face and curved longitudinally in an involute curve or a curve approximating thereto; and assembled with the corrugated face of each in contact with the other face of an adjacent tube to provide air passages between the corrugations. One face of each tube may be flat and engage the internal crest of the corrugations in the other face, and the tubes may be assembled with the external crest of the corrugations on each engaging the flat face of an adjacent tube, preferably with the corrugated face of each tube outermost.

Eachtube may be formed by longitudinally tube. The end elements may also form the.

means for securing the tubes on a rotatable support for the burner. The end element at the fuel-delivery end of each tube may also be shaped to provide an air scoop between itself and the adjacent like end elements so as to assist the circulation of airthrough air passages between the tubes.

An intemal-combustion turbine incorporating the present invention will now be described, by way of example only, with-reference to the ac companying drawings in which:

Figure 1 is a plan, partly in section, of the turbine. This figure is diagrammatic.

Figure 2 is a section, on a larger scale, on the line .2-2 of Figure 3,'through a burner and air cooler in the turbine; v

Figure 31s a section on the line 3-3 of Figure 2 and shows the cooler elements;

Figure 4 is a side elevation of-one cooler element;

Figures 5 and 6 are elevations of the cooler element shown in Figure 4 as seen when looking in the direction of the arrows 5 and 6 respectively in Figure 4;

Figure '7 is a section, on a larger scale, on the line 11 of Figure 4, and v Figure 8 is a plan of a blanl: from which a cooler element is made.

As shown in Figure 1, the turbine comprises a stationary shaft in which is supported by suitable bearings from two sets of streamlined struts I2 and I3 which, in turn, are carried by an annular tunnel (not shown) surrounding the rear end, right-hand end in Figure 1, of the turbine. The struts l3 also support a casing M for the high-pressure part of the turbine and an outer casing l5 that encloses the forwardparts of the turbine. A set of rotors it are mounted to rotate on the shaft l0 and are formed each with an inner ring of shrouded compressor blades i1, an outer ring of shrouded turbine blades is and a set of propeller blades I! that rotate in the annular tunnel aforesaid.

The rotors |6 are arranged alternately to rotate in opposite directions and provide a propulsive thrust by means of their blades l9. A second setof blades 26 are mounted to rotate on the shaft l6 within the casing l6 and have each an inner ring of shrouded compressor blades 2| and an outer ring of shrouded turbine blades 22. The last rings of compressor and turbine blades to the left are stator blades and are carried by an annular stator 23 secured to the casing. The third rings of compressor and turbine blades from the left are also stator blades and are carried by a stator 24 which serves to support the forward end of the shaft i6.

Air enters the unit through forwardly directed air-intakes 25 and a passage 26 into an annular chamber 21. The air passes from the chamber 21 through a ring of stator blades 28 to the compressor blades H which compress the air and deliver it to the compressor blades 2|. These blades further compress the air and deliver it 4 rial, which has its two end portions 59 and 66 and its centre portion 6| of the same width.

through an annular diverging passage 29 to an annular combustion chamber 36. Fuel is burnt in the air by means of a burner assembly generally designated 3| and the products of combustion pass through an annular converging passage 32 to the first ring of turbine blades 22. The products of combustion then expand through the turbine blades 22 and I6 and are discharged rearwardly from the last ring of turbine blades.

The construction described above forms the subject-matter of the co-pending application Serial No. 505,389 by A. A. Grifilth, filed October 7, 1943 (British application No. 4,699/41), and is more fully described therein. The present improvements will now be described.

The burner assembly comprises a disc 46 carried by a shaft 4| that rotates in bearings 42 carried by a casing 43. This casing is supported from the casing l4. The shaft 4| is ranged to operate as a generator when the tur-' bine is running.

The burner assembly also comprises an annular disc 48 of which the hub 49 rotates on the cylindrical outer surface of a stationary distributing ring 56. The hub of this disc is formed with'an annular groove 5| which acts as a collecting ring for fuel and is fitted with suitable seals to prevent leakage of fuel between it and the distributing ring. Fuel is supplied to the collecting ring by a conduit 52, a connection box 63, six conduits 54 (of which one only is shown) and six valve chambers 55 spaced equally around the distributing ring 56. Each valve chamber contains a non-retum valve 56 and the fuel leaves it through a passage 51 to enter the collecting ring 5|. The fuel flows from the collecting ring 5| through twelve tubes 58 (see also Figure 3) whose construction will be described later, to the twelve burners 46 which are arranged in a circle around the periphery of the disc 46. The construction of these tubes 56 is as follows:

Each tube is formed from a sheet metal strip, shown in Figure 8, brass being a suitab m te- The portion 62 is reduced in width while the portion 63 is increased in width. The reduced portion 62 is corrugated longitudinally at 64 with three, or any other number of, corrugations which extend beyond the ends of the reduced portion into the central portion 6| and the adjacent end portion 59. The remainder of the strip is fiat and the length of the wider portion 63 is the same as that of the reduced portion. 62 and is several times the length of each end portion 59 and 60 and of the central portion 6|. This strip is bent about its centre so that the reduced portion 62 registers with the wider portion 63 and the central portion 6| forms a loop. The edges 65 of the wider portion 63 are then folded over the edges of the reduced portion 62, as shown in Figure 7, so as to bring the outer face of the folded edge flush with the edges of the end and central portions 59. 66 and 6|. The joints between the edges of the wider and reduced portions 62 and 63 are then soldered, preferably with silver solder, so as to form a closed flattened tube in which the inner crests of each corrugation lie against the inner face of the opposite flat side of the tube, as shown in Figure '7. The spaces within the corrugations form fuel passages. After the side edges of the tube are hard soldered together, the whole flattened tube is curved, as shown in Figure 4, to form an involute with the corrugated face outermost and with the loop formed by the central portion of the blank nearer the base circle of the invoiuate than the other end of the tube.

The loop 6| in the tube receives an inner end element 66 (Figures 4 and 6) having a part cylindrical portion merging into a tapered tail. A spigot 61 projects from one side of the end element 66 and is concentric with the cylindrical portion thereof and a bore 66 is formed through this spigot and extends completely through the element. The end 69 of this bore remote from the spigot 61 is screw-threaded and is closed beyond the screw-threaded portion by a blanking disc 16. Passages 1| are-formed in the tail portion of the element 66 so as to provide communication from the bore 66 to the corrugations in the tube 58. Fuel can thus flow through the bore of the end element into the tube and hence to its outer end.

The ends 59 and 66 of the strip at the outer end of the tube 56 are splayed apart to receive an outer end element 12 which is of approximately aerofoil shape and has a nose portion 13. The outer end element has a bore 14 that extends completely through it and passages 15 in the tail that place the interior of the tube 58 in communication with the bore 14. This element 12 also carries a stud 16 and is inserted between the splayed portions 59 and 66 of the outer end of the tube 56 which portions are folded over it so as to meet at their ends where they are joined by being soldered to the end element. Both the end elements 66 and 12 are hard soldered in position so as completely to close the tube except for the inlet and outlet through the bores 66 and 14 of the end elements.

The spigot 61 on the inner end element of each tube 58 fits into one of a number of sockets 11 spaced around the annular disc 46 (Figure 2) near its inner edge. The inner end element 66, and therefore the inner end of the tube, is secured in position by a set-screw 16 passing through the annular disc 46 and the 'bore 66 in lies between the two discs 40 and 48 and its width is the same as the space between them. The

, outer end of the tube is secured in position by means of a hollow burner bolt I9 which passes through both discs and through the bore in the outer end element I2. The burner bolt 18 is perforated at 80 so that the fuel flowing through the tube can pass through the outer end element in the burner bolt and thence to the burner. It

will be understood that there is a separate burner bolt for each tube and that these burner bolts are equally spaced around the periphery of the supporting discs. Each burner bolt also holds to burners on the assembly and conveys the fuel from its tube 58 to the openings in the burner through which it is injected into the air stream. Each stud 18 extends through a hole in the disc 48 and receives a nut so that each end element 12 is held to two spaced points'and cannot be turned by the air pressure on it due to the rotation of the assembly.

The number (in the case shown, twelve) of tubes 58 and their length are so selected that, being of involute shape and of even thickness, they pack'tightly together with the crests of the corrugations 54 in one face of each tube in contact with the flat face 63 of the adjacent tube. A number of shallow air passages is thus provided between each pair of adjacent tubes and each passage extends spirally through the annular pack of tubes so as to open at one end through the outer surface of the pack and at the other end into the space 82 within the pack. The outer ends 8| (Figure 3) of the air passages communicate with an annular space 85 partitioned off from the combustion chamber 30 so that some of the compressed air will be delivered into this chamber and will enter the outer ends ll of the air passages and flow along them to the space '2 inside the pack of tubes. The air flowing through the air passages is cooled by the fuel flowing through the tubes in the opposite direction and the cooled compressed air can be led away from the central space inside the pack of tubes, through openings 83 in the disc 40 and the space within an annular partition 84, to the turbine bearings where it is employed to balance the gas pressure acting on the turbine'discs and for cooling the bearings as described in application Serial v NO. 505,391 by A. A. Grimth, flied October 7, 1943,

now Patent No. 2,429,681 (British application No. 5,152/41).

It will be seen that the construction provides a very compact form of air-cooler having very long narrow air passages and correspondingly long and narrow fuel passages for the fuel which constitutes a cooling medium. The corrugations N are on the outer side of each fuel tube so that the fuel will tend to be thrown into the corrugations by centrifugal action and to flow along the corrugations where it exerts a maximum cooling efiect on the air to be cooled.

Ignoring the outer end element 12 of each tube 58, the outer surface of the assembly of tubes is roughly cylindrical. The outer end elements 12 of the tubes project beyond the cylindrical surface as shown in Figure 2 and the nose part 73 of each end element is so shaped that it provides a divergent entrance 8| to the air passages between its tube and an adjacent tube. These divergent entrances ll act as air scoops and face .in the direction of rotation of the burner and air-cooler assembly so that air is forced into passages by the rotation of the assembly. The construction thus provides for a considerable mass flow of air through thecooler and for efllcient cooling of the air flowing through it. The end elements it and I! serve to support the tubes I. in the assembly as well as to provide communication between the interior of the tube and the collector ring I and burner bolts I! respectively.

The tubes II are shown as being of uniform depth throughout their length and provide air passages of uniform cross-sectional area. The

area of the air passages can be made to vary from one end to the other by making the depth of each tube vary also and in this case each tube would be bent to a curve which is only approximately an involute in order that they should pack tightly.

the compressor delivers compressed air, a burner unit rotating in the combustion chamber, delivering fuel thereto, and comprising a collecting ring rotating with the burner unit and a stationary fuel feed to that ring, a turbine through which the I products of combustion from the combustion chamber expand and an air cooler constituted by a plurality of passages rotating with the burner, connecting and conveying fuel from the collecting ring to the burner and spaced apart to provide betweenthem air passages communicating at one end with the delivery from the compressor and atthe other end with a space in which cooled compressed air is required.

2. An internal-combustion turbine comprising a compressor, a combustion chamber into which the compressor delivers compressed air, a burner unit rotating in the combustion chamber, delivering fuel thereto, a collecting ring rotating with the burner unit and a stationary fuel feed to that ring, a turbine through which the products of combustion from the combustion chamber expand and an air cooler constituted by a plurality of burners arranged in a circle about the axis of rotation, and a plurality of passages, which passages each connect, and convey fuel from, the collect- .ing ring to a separate burner and are spirally arranged around the axis of rotation of the burner to rotate therewith and spaced apart to provide between them air passages of each of which one end communicates with the delivery from the compressor and faces in the direction of rotation around the axis of rotation of the burner unit, a

collecting ring rotating with the burner unit and ,a stationary fuel feed to that ring, a turbine through which the products of combustion from the combustion chamber expand and an air cooler which comprises a plurality of flattened tubes each longitudinally corrugated on one face and curved longitudinally in an approximately involute curve, which tubes are mounted on the burner unit with the corrugated face of each in contact with the other facelof an adjacent tube to provide air passages between the corrugations and with one end of each tube communicatin with a separate burner and the other end communicating with the collecting ring.

4. An internal-combustion turbine comprising a compressor, a combustion chamber lntowhich the compressor delivers compressed air, a burner unit rotatable within the combustion chamber and comprising a number of burners spaced around the axis of rotation of the burner unit, a collecting ring rotating with the burner unit and a stationary fuel feed to that ring, a turbine through which the products of combustion from the combustion chamber expand and an air cooler which comprises a plurality of flattened tubes each connecting the collecting ring to a separate burner and each longitudinally corrugated on one face and having the opposite face flat and in engagement with the internal crests of the corrugations, and each curved longitudinally in a substantially involute curve, which tubes are assembled together on the burner unit to rotate therewith with the corrugated face of each in contact with the flat face of an adjacent tube to provide air passages between the corrugations, each of which passages communicates at one end with the combustion chamber through a, mouth opening in the direction of rotation of the burner unit and at the other end with a space within which cooled compressed air is required.

5. An internal-combustion turbine according to claim 4 wherein each tube is curved to bring its corrugated face outermost.

6. In an internal-combustion turbine, the combination with a rotating burner unit having a number of burners equally spaced in a circle around the axis of rotation of the burner unit to rotate therewith, a collecting ring rotating with the burner and a stationary fuel feed to that ring, of an air cooler comprising a, plurality of flattened tubes each communicating at one end with a separate burner and at the other end with the c01 lecting ring to convey fuel from the ring to the burner and each having one face longitudinally corrugated and the opposite face flat and in contact with the internal crests of the corrugations,

which tubes are supported on the burner unit to I burner and also open internally of the assembly of tubes.

7. In an internal-combustion turbine, the combination with a rotating burner unit comprising a plurality of burners equally spaced in a circle around the axis of rotation of the unit to rotate therewith, a collecting ring and a, stationary fuel feed to the collecting ring, of an air cooler comprising a plurality of tubes assembled on the burner unit to rotate therewith each connecting the collecting ring to a separate burner, and col-- lectively providing a plurality of air passages between them, each of which tubes is formed by longitudinally corrugating a sheet metal strip, folding one half of the strip over on to the other and securing the two halves together along each of their abutting edges.

8. The combination according to claim '1 wherein each strip is folded about a transverse line intermediate its ends and a portion of the strip on one side of the said line is wider than the mating portion of the other side of said line to provide marginal strips of the first portion which extend beyond both edges of the second portion and are folded thereover and secured thereto to form the tube.

9. In an internal-combustion turbine, a rotating burner unit comprising a rotatable support, a. plurality of burners mounted on the support in a circle around its axis of rotation, a collecting ring formed in the support, stationary means for feeding fuel to the collecting ring, a plurality of flattened tubes each curved longitudinally substantially to an involute and assembled on the support each to provide communication from the collecting ring to a separate burner, and to provide between them a plurality of narrow air passages extending from an approximately cylindrical outer surface of the assemblage of tubes to the inside of the assemblage of tubes, the outer end of each of which tubes is so shaped that it extends approximately tangentially of the assembly and in the direction of rotation of the support to provide, between itself and the end of an adjacent tube, an air scoop which leads to one of the air passages and ensures an air flow therethrough.

DONALD EYRE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 984,911 Harris et al Feb. 21, 1911 1,015,404 Schewczik Jan. 23, 1912 1,110,065 Linga Sept. 8, 1914 1,610,651 Blaetz Dec. 14, 1926 1,960,810 Gordon May 29, 1934 2,019,879 Wahlstrom "-1 Nov. 5, 1935 

